Stent design

ABSTRACT

A stent comprises at least one band of interconnected cells selected from the group consisting of S-shaped cells and mirror image S-shaped cells. Each cell has a top end and a bottom end. The top end of each cell is attached to the bottom end of an adjacent cell in the band. Adjacent bands may abut one another or may be joined by connecting members.

BACKGROUND OF INVENTION

[0001] A stent is a structure which is designed to maintain the patencyof a bodily vessel. Stents are delivered to a desired bodily location inan unexpanded configuration having a reduced cross-section and expandedto a configuration having an increased cross-section. Stents aretypically self-expandable or mechanically expandable. Examples ofself-expandable and mechanically expandable stents are disclosed in WO9626689 and U.S. Pat. No. 6,042,597.

[0002] It is desirable for a stent to be flexible in the unexpandedconfiguration to facilitate delivery of the stent through tortuousvessels and to have a sufficient degree of rigidity in the expandedconfiguration to support a vessel. It is also desirable for a stent inthe expanded configuration to provide sufficient vessel coverage.

[0003] Although a vast number of stent designs have been disclosed inrecent years, there remains a need for innovative stent designs whichare flexible in the unexpanded configuration and which exhibit improvedcoverage characteristics in the expanded configuration. There alsoremains a need for stents with improved expansion ratios relative tocurrent stents.

[0004] All U.S. patents and applications and all other publisheddocuments mentioned anywhere in this application are incorporated hereinby reference in their entirety.

[0005] The invention in various of its embodiment is summarized below.Additional details of the invention and/or additional embodiments of theinvention may be found in the Detailed Description of the Inventionbelow.

SUMMARY OF INVENTION

[0006] In one embodiment, the invention is directed to a stentcomprising at least one band of interconnected cells selected from thegroup consisting of circumferentially oriented S-shaped cells andcircumferentially oriented mirror image S-shaped cells. Each cell has atop end and a bottom end. The top end of each cell is attached to thebottom end of an adjacent cell in the band. The stent may comprise aplurality of interconnected bands of interconnected S-shaped cellsand/or mirror image S-shaped cells. Where bands of S-shaped cells andbands of mirror image S-shaped cells are present, the bands mayalternate over the length of the stent or be provided in any othersuitable arrangement. Adjacent bands of S-shaped cells and/or mirrorimage S-shaped cells may abut one another or may be joined by connectingmembers. Where connecting members are provided, the members may bestraight or may have one or more bends therein. The stent may have asingle type of connecting member or multiple types of connectingmembers. Adjacent connecting members may be joined to one another toform differently shaped cells. In one embodiment, the differently shapedcells are generally arrow shaped.

[0007] The invention is also directed to a stent comprising at least onecell selected from the group consisting of S-shaped cells and mirrorimage S-shaped cells.

[0008] The invention is also directed to stents comprising at least oneband formed of a plurality of substantially X-shaped members. EachX-shaped member has a proximal end and a distal end and includes a firstarm of a first length, a second arm of a second length different fromthe first length, a third arm of a third length and a fourth arm of afourth length different from the third length. The first and second armsextend in a distal direction and the third and fourth arms extend in aproximal direction. Adjacent X-shaped members are joined together at thedistal end by a first loop member extending there between and at theproximal end by a second loop member extending therebetween. The firstloop member and the second loop are non-parallel to the longitudinalaxis of the stent. The first loop member includes a first loop orientedsubstantially in the proximal direction and a second loop orientedsubstantially in the distal direction and the second loop memberincludes a first loop oriented substantially in the proximal directionand a second loop oriented substantially in the distal direction.Adjacent bands of substantially X-shaped members may abut one another ormay be joined by connecting members extending therebetween. Whereconnecting members are provided, the members may be straight or may haveone or more bends therein. The stent may have a single type ofconnecting member or multiple types of connecting members. Adjacentconnecting members may be joined to one another to form differentlyshaped cells. In one embodiment, the differently shaped cells aregenerally arrow shaped.

[0009] The invention is also directed to a stent comprising one or morecells with each cell consisting of two inwardly pointing fingers, one ofwhich opens in a proximal direction and the other of which opens in adistal direction. The closed portion of the finger which opens in thedistal direction is located proximal of the closed portion of the fingerwhich opens in the distal direction.

BRIEF DESCRIPTION OF DRAWINGS

[0010]FIG. 1 shows a flat pattern of an embodiment of the inventivestent in an unexpanded configuration.

[0011]FIG. 2 shows a flat pattern of another embodiment of the inventivestent in an unexpanded configuration.

[0012]FIG. 3 shows a flat pattern of another embodiment of the inventivestent in an unexpanded configuration.

[0013]FIG. 4 shows a flat pattern of another embodiment of the inventivestent in an unexpanded configuration.

DETAILED DESCRIPTION

[0014] While this invention may be embodied in many different forms,there are described in detail herein specific preferred embodiments ofthe invention. This description is an exemplification of the principlesof the invention and is not intended to limit the invention to theparticular embodiments illustrated.

[0015] For the purposes of this disclosure, unless otherwise indicated,identical reference numerals used in different figures refer to the samecomponent.

[0016]FIG. 1 illustrates in flattened form one of the embodiments of thestent of the present invention in an unexpanded configuration. Thestent, shown generally at 100 in FIG. 1 has a proximal end 102, a distalend 104 and is composed of a plurality of interconnectedcircumferentially oriented S-shaped cells 106 (one of which is shownhighlighted) and circumferentially oriented mirror image S-shaped cells108 (one of which is shown highlighted). The longitudinal axis 212 ofthe stent corresponds to the direction of flow in the stent. EachS-shaped cell 106 has a top end 110 and a bottom end 112 and a proximalend 114 and a distal end 116. Each mirror image S-shaped cell 108 has atop end 118 and a bottom end 120 and a proximal end 122 and a distal end124.

[0017] Adjacent S-shaped cells are connected top-to-bottom with top end110 of an S-shaped cell abutting bottom end 112 of an adjacent S-shapedcell to form a band 126 of S-shaped cells. Similarly, adjacent mirrorimage S-shaped cells are connected top-to-bottom with top end 118 ofmirror image S-shaped cell 108 abutting bottom end 120 of an adjacentmirror image S-shaped cell to form a band 128 of mirror image S-shapedcells. Bands 126 of S-shaped cells alternate along the length of thestent with bands 128 of mirror image S-shaped cells. Distal ends 116 ofS-shaped cells 106 are joined to proximal ends 122 of mirror imageS-shaped cells. Similarly, distal ends 124 of mirror image S-shapedcells 108 are joined to proximal ends 114 of S-shaped cells 106.

[0018] The stent shown in FIG. 1 terminates on the proximal end 102 in aband 128 of mirror image S-shaped cells 108 and on the distal end 104 ina band 126 of S-shaped cells 106. The invention also contemplates otherarrangements as well including embodiments in which the stent terminatesin S-shaped cells in the proximal end and mirror image S-shaped cells inthe distal end. Moreover, both ends may terminate in a band of S-shapedcells or in a band of mirror image S-shaped cells. The invention furthercontemplates the possibility of one or more of the ends of the stentterminating in bands other than those containing S-shaped cells ormirror image S-shaped cells.

[0019] In the embodiment of FIG. 1, bands of S-shaped cells 126alternate along the length of the stent with bands 128 of mirror imageS-shaped cells. The invention also contemplates inventive stentcomprising one or more bands of S-shaped cells and one or more bands ofmirror image S-shaped cells where the bands do not alternate with oneanother over the length of the stent. In the embodiment of FIG. 2, forexample, with the exception of distal end 104 of stent 100, S-shapedcells 126 are provided in groupings of two and mirror image S-shapedcells 128 are provided in groupings of two, which alternate with oneanother over the length of stent. The stent of FIG. 2 may also bemodified to provide a grouping of two mirror image S-shaped cells at thedistal end of the stent. Other modification include replacing theS-shaped cells with mirror image S-shaped cells and replacing mirrorimage S-shaped cells with S-shaped cells. Further in accordance with theinvention, the bands of S-shaped cells and/or the bands of mirror imageS-shaped cells may be provided in groups of three, four or more bands.

[0020] Where bands of S-shaped cells abut one another, substantiallyparallelogram shaped first openings 192 are formed between adjacentbands of S-shaped cells. Similarly, bands of mirror image S-shaped cellsabut one another, substantially parallelogram shaped second openings 194are formed between adjacent bands of mirror image S-shaped cells. Theorientation of substantially parallelogram shaped first and secondopenings are opposite one another.

[0021] The invention is also directed to a stents, such as that shownfor example in FIG. 2, comprising cells with substantially polygonalshaped first openings 192 extending in a first direction, wherecircumferentially adjacent cells having substantially polygonal shapedfirst openings are joined by one or more looped portions 214. Desirably,as shown in FIG. 2, circumferentially adjacent cells havingsubstantially polygonal shaped first openings 192 are joined by at leasttwo looped portions 214 and 220 which generally open toward one another.As shown in FIG. 2, the substantially polygonal shaped first openingsare in the form of parallelograms. Cells with other substantiallypolygonal openings including triangular opening, pentagonal openings andhexagonal openings may be used in other embodiments of the invention.

[0022] Optionally, as shown in FIG. 2, the stent may include cells withopenings 192 which extend in a first oblique direction relative to thelongitudinal axis of the stent and cells with openings 194 which extendin a second oblique direction relative to the longitudinal axis of thestent. Desirably, the first and second oblique directions are oppositeone another.

[0023] The inventive stent may also be made exclusively of one or morebands of S-shaped cells or exclusively of one or more bands of mirrorimage S-shaped cells.

[0024] The invention also contemplates providing interconnectingelements between adjacent bands of S-shaped cells and/or mirror imageS-shaped cells. The unexpanded stent of FIG. 3, shown generally at 100in FIG. 3 in a flat pattern, comprises alternating bands 126 of S-shapedcells 106 and bands 128 of mirror image S-shaped cells 108. Thelongitudinal axis 212 of the stent corresponds to the direction of flowin the stent. Extending between adjacent bands are first connectingmembers 132 and second connecting members 144.

[0025] First connecting members 132 have a proximal end 138, a distalend 140, a middle portion 134 therebetween and a single bend 142 betweenproximal end 138 and distal end 140. As the stent is traversed from theproximal end to the distal end, first connecting members 132 extend fromthe distal ends of S-shaped cells (and mirror image S-shaped cells) tothe proximal ends of adjacent S-shaped cells (and mirror image S-shapedcells).

[0026] Second connecting members 144 have a proximal end 150, a distalend 152, a middle portion 146 therebetween and three bends 154 betweenproximal end 150 and distal end 152. As the stent is traversed from theproximal end to the distal end, second connecting members 144 extendfrom the distal ends of S-shaped cells (and mirror image S-shaped cells)to the proximal ends of adjacent S-shaped cells (and mirror imageS-shaped cells). Middle portions 134 of first connecting members 132 areconnected to middle portions 146 of adjacent second connecting members144 to form differently shaped cells in the form of arrow cells 156 (oneof which is shown highlighted).

[0027] In the embodiment of FIG. 3, arrow cells 156 are disposed inbands 158 about the periphery of the stent. The orientation of bands 158of arrow cells 156 alternates along the length of the stent. Arrow cells156 a are oriented in a first circumferential direction and arrow cells156 b are oriented opposite to arrow cells 156 a. The invention alsocontemplates a stent where the orientation of the arrow cells does notalternate over the length of the stent.

[0028] The stent of FIG. 3 is provided with several additional types ofcells. Third types of cells 160, fourth types of cells 162, fifth typesof cell 164 and sixth types of cell 166 (one of each of which is shownhighlighted) are provided bounded by arrow cells on one side andS-shaped cells or mirror image S-shaped cells on the other side. Thethird, fourth, fifth and sixth types of cells are related to one anothervia various symmetry operations. For example, fourth type of cell 162 asseen in the flat pattern of FIG. 3, is a mirror image of third type ofcell 160 about an axis 168 which bisects arrow cells 156. Fifth type ofcell 164 is a mirror image of third type of cell 160 about thelongitudinal axis 212 of the stent. Finally, sixth type of cell 166 is amirror image of fifth type of cell 164 about axis 168.

[0029] As shown in FIG. 3, the struts forming first connecting members132 and second connecting members 144 are not as wide as the strutsforming the S-shaped cells and the mirror image S-shaped cells. Theinvention also contemplates embodiments in which the struts forming thefirst and second connecting members are as wide as or wider than thestruts forming the S-shaped cells and the mirror image S-shaped cells.

[0030] Further as shown in FIG. 3, arrow cells 156 are longer in thelongitudinal direction than the S-shaped cells and mirror image S-shapedcells. The invention also contemplates embodiments in which the S-shapedcells and mirror image S-shaped cells are of the same longitudinallength or are longer longitudinally than the arrow shaped cells.

[0031] In the embodiment of FIG. 3, proximal end 102 of stent 100terminates in band 158 of arrow cells 156, one of which is shownhatched, and distal end 104 of stent 100 terminates in a band 126 ofS-shaped cells. It is also within the scope of the invention for bothends of the stent to terminate in a band of arrow cells. As shown inFIG. 4, distal end 104 of stent 100 terminates in a band 158 b of arrowcells 156 b having an orientation opposite to that of the proximal-mostband 158 a of arrow cells 156 a. In accordance with the invention, wherea band of arrow shaped cells is provided at both ends of the stent, theorientation of arrows at both ends of the stent may be identical. It isfurther within the scope of the invention for both the proximal anddistal ends of the stent to terminate in a band of S-shaped cells, aband of mirror image S-shaped cells or a band of S-shaped cells at oneend of the stent and a band of mirror image S-shaped cells at the otherend of the stent.

[0032] The invention further contemplates embodiments in which thenumber of cells in band varies in various portions of the stent. Forexample, a stent may be provided having bands consisting of ‘N’ S-shapedcells and bands consisting of ‘N’ mirror image S-shaped cellsalternating with bands having ‘M’ arrow cells where ‘M’ is less than‘N’. A stent may also be provided in which the number of arrow cells ‘M’in a band exceeds the number of S-shaped or mirror image S-shaped cells‘N’ in a band.

[0033] In another embodiment, the invention is directed to stents havingproperties which vary along the length of the stent. This may beachieved in a stent in which the number of S-shaped cells and/or mirrorimage S-shaped cells per band increases along the length of the stent.This may also be achieved in a stent where both ends have more S-shapedcells and/or mirror image S-shaped cells than the middle section of thestent or in a stent where the ends have fewer S-shaped cells and/ormirror image S-shaped cells than the middle of the stent. Otherembodiments that are within the scope of the invention includeembodiments in which the length and or the width and/or the aspect ratioof the S-shaped cells and/or mirror image S-shaped cells is varied overthe length of the stent.

[0034] The invention is also directed to stents having bands of S-shapedcells and/or mirror image S-shaped cells joined together with any othertype of connecting member. Connecting members of a different lengthand/or with bends of a different geometry may be provided. Adjacentconnecting members may be of different lengths as shown in FIG. 2 or maybe of the same length. The connecting members may also be straight.

[0035] More generally, the invention is also directed to stents havingat least one S-shaped cell and/or at least one mirror image S-shapedcell. Where a plurality of such cells is present, the cells may abut oneanother or may be spaced apart in the stent. As discussed above, thecells may be provided in one or more interconnected bands. Each band mayconsist of a single type of cell, whether S-shaped or mirror imageS-shaped, or may consist of both S-shaped cells and mirror imageS-shaped cells.

[0036] The invention is also directed to stents comprising at least oneband, formed of a plurality of substantially X-shaped members. As shownin FIG. 1, each X-shaped member 202 has a proximal end 204 and a distalend 206. Adjacent X-shaped members 202 are joined together at distal end206 by a first loop member 208 extending therebetween and at proximalend 204 by a second loop member 210 extending therebetween. First loopmember 208 and second loop member 210 are non-parallel to thelongitudinal axis 212 of the stent.

[0037] First loop member 208 includes a first loop 214 orientedsubstantially in the proximal direction, a second loop 216 orientedsubstantially in the distal direction and a third loop 215 orientedsubstantially in the distal direction. The shape of the first, secondand third loops forming the first loop member differ from one anotherwith first loop 214 having a more bulbous shape than second loop 216 andthird loop 215. First and second loops having other geometries as wellmay also be provided.

[0038] Second loop member 210 includes a first loop 218 orientedsubstantially in the proximal direction, a second loop 220 orientedsubstantially in the distal direction and a third loop 221 orientedsubstantially in the proximal direction. The shape of the first secondand third loops forming the second loop member differ from one anotherwith second loop 220 having a more bulbous shape than first loop 218 andthird loop 221.

[0039] First and second loops having other geometries as well may alsobe provided.

[0040] Each X-shaped member 202 includes first arm 222 of a firstlength, second arm 224 of second length different from the first length,third arm 226 of a third length and fourth arm 228 of a fourth lengthdifferent from the third length. First 222 and second arm 224 extend ina distal direction and third arm 226 and fourth arm 228 extend in aproximal direction.

[0041] The inventive stent may have one or more bands 230 formed of oneor more substantially X-shaped members 202. As shown in FIG. 1, adjacentbands 230 formed of a plurality of substantially X-shaped members mayabut one another. As shown in FIG. 3, the invention is also directed tostents where adjacent bands 230 formed of substantially X-shaped members202 may be joined by connecting members extending therebetween. A singletype of connecting member may join adjacent bands of X-shaped members(not shown) or a plurality of types of connecting members may joinadjacent bands. The stent of FIG. 3 is provided with first connectingmembers 132 and second connecting members 144 extending between adjacentbands 230. As discussed above, first connecting member 132 has a singlebend therein and second connecting member 144 has three bends therein.Other shaped connecting members may also be provided.

[0042] The invention is also directed to stents in partially expandedand fully expanded configurations having structures such as those shownin FIGS. 1-4.

[0043] The invention is also directed to a stent comprising one or morecells with each cell consisting of two inwardly pointing fingers, one ofwhich opens in a proximal direction and the other of which opens in adistal direction. The closed portion of the finger which opens in thedistal direction is located proximal of the closed portion of the fingerwhich opens in the distal direction. An example of such an embodiment isshown in FIG. 2. Cell 106 comprises a first inwardly pointing finger 310and a second inwardly pointing finger 312. Finger 310 opens in aproximal direction and finger 312 opens in a distal direction. Closedportion 316 of finger 312 is located proximal of closed portion 314 offinger 310.

[0044] The inventive stents disclosed herein may be self-expanding ormechanically expandable (including balloon expandable). They may be madeof any suitable material including metal or polymeric material. Suitablemetals include stainless steel, titanium, gold and shape memorymaterials such as nitinol. The stents may be formed of more than onemetal and may include various radiopaque coatings such as a thin layerof gold or other radiopaque metal. Other biocompatible coatings may beprovided as well including lubricious coatings as are known in the art.

[0045] The stents may be laser cut, chemically etched, electrodischargemachined or cut using any other suitable technique from a tube. Thestent pattern may also be cut into a sheet using any of theabove-mentioned techniques and the sheet rolled into tubular form andthe ends welded or otherwise joined together. The inventive stentdesigns may also be used in coiled sheet stents where the sheet whichforms the stent is formed into a roll which may unroll to a wideropening.

[0046] The above disclosure is intended to be illustrative and notexhaustive. This description will suggest many variations andalternatives to one of ordinary skill in this art. All thesealternatives and variations are intended to be included within the scopeof the claims where the term “comprising” means “including, but notlimited to”.

[0047] Those familiar with the art may recognize other equivalents tothe specific embodiments described herein which equivalents are alsointended to be encompassed by the claims.

[0048] Further, the particular features presented in the dependentclaims can be combined with each other in other manners within the scopeof the invention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below (e.g. claim 3 may be taken asalternatively dependent from claim 1; claim 5 may be taken asalternatively dependent on claim 3; claim 6 may be taken asalternatively dependent from claim 4 or claim 5; etc.).

[0049] The above Examples and disclosure are intended to be illustrativeand not exhaustive. These examples and description will suggest manyvariations and alternatives to one of ordinary skill in this art. Allthese alternatives and variations are intended to be included within thescope of the attached claims. Those familiar with the art may recognizeother equivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the claims attachedhereto.

1. A stent comprising at least one band of interconnected cells selectedfrom the group consisting of circumferentially oriented S-shaped cellsand circumferentially oriented mirror image S-shaped cells, each cellhaving a top end and a bottom end, the top end of each cell attached tothe bottom end of an adjacent cell in the band.
 2. The stent of claim 1comprising a plurality of interconnected bands of interconnectedS-shaped cells.
 3. The stent of claim 2 further comprising a pluralityof bands of interconnected mirror image S-shaped cells.
 4. The stent ofclaim 3 wherein the bands of interconnected S-shape cells alternate withthe bands of interconnected mirror image S-shaped cells over the lengthof the stent.
 5. The stent of claim 4 wherein adjacent bands ofinterconnected S-shaped cells and interconnected mirror image S-shapedcells abut one another.
 6. The stent of claim 3 consisting only of bandsof interconnected S-shaped cells and bands of interconnected mirrorimage S-shaped cells.
 7. The stent of claim 4 wherein adjacent bands ofinterconnected S-shaped cells and interconnected mirror image S-shapedcells have connecting members extending therebetween.
 8. The stent ofclaim 7 wherein the connecting members have at least one bend therein.9. The stent of claim 4 wherein adjacent bands of interconnectedS-shaped cells and interconnected mirror image S-shaped cells have firstconnecting members of a first length and second connecting members of asecond length different from the first length extending therebetween.10. The stent of claim 9 wherein each first connecting member isconnected to an adjacent second connecting member.
 11. The stent ofclaim 4 wherein adjacent bands of interconnected S-shaped cells andbands of interconnected mirror image S-shaped cells have bands ofdifferently shaped cells therebetween, the differently shaped cellsdiffering in shape from the S-shaped cells and from the mirror imageS-shaped cells.
 12. The stent of claim 11 wherein the differently shapedcells are in the shape of an arrow.
 13. The stent of claim 12 whereinthe arrows are oriented in a circumferential direction.
 14. The stent ofclaim 13 wherein adjacent bands of differently shaped cells are orientedin opposing circumferential directions.
 15. A stent comprising at leastone cell selected from the group consisting of circumferentiallyoriented S-shaped cells and circumferentially oriented mirror imageS-shaped cells.
 16. A stent comprising at least one band, the bandformed of a plurality of substantially X-shaped members, each X-shapedmember having a proximal end and a distal end, adjacent X-shaped membersjoined together at the distal end by a first loop member extendingtherebetween and at the proximal end by a second loop member extendingtherebetween.
 17. The stent of claim 16 wherein the first loop memberand the second loop member are non-parallel to the longitudinal axis ofthe stent.
 18. The stent of claim 16 wherein the first loop memberincludes a loop oriented substantially in the proximal direction and asecond loop oriented substantially in the distal direction and thesecond loop member includes a loop oriented substantially in theproximal direction and a second loop oriented substantially in thedistal direction.
 19. The stent of claim 16 wherein each X-shaped memberincludes a first arm of a first length and a second arm of a secondlength different from the first length, the first and second armsextending in a distal direction and a third arm of a third length and afourth arm of a fourth length different from the third length, the thirdand fourth arms extending in a proximal direction.
 20. The stent ofclaim 16 comprising a plurality of connected bands formed of a pluralityof substantially X-shaped members.
 21. The stent of claim 20 whereinadjacent bands formed of a plurality of substantially X-shaped membersabut one another.
 22. The stent of claim 20 wherein adjacent bandsformed of a plurality of substantially X-shaped members are joined byconnecting members extending therebetween.
 23. The stent of claim 22wherein adjacent bands formed of a plurality of substantially X-shapedmembers are joined by first connecting members of a first length andsecond connecting members of a second length extending therebetween, thesecond length different from the first length.
 24. A stent comprising atleast cell, the cell consisting of a first inwardly pointing finger anda second inwardly pointing finger, the first inwardly pointing fingeropening in a proximal direction and having a closed portion at a distalend, the second inwardly pointing finger opening in a distal directionand having a closed portion at a proximal end, the closed portion of thesecond inwardly pointing finger located proximal of the closed portionof the second inwardly pointing finger.